bending a flange in .050

I'm trying to bend the flange on the bottom of the instrument panel in the -4
It is 2024-T3, .050, plans say min 1/4 radius.

tried some practice bends on a brake at work, but the radius is too tight and I see cracks in the bend. Our brake has no adjustment for radius.

any good tips out there how to make this bend without a brake?

I tried to make a similar bend

in .062 2024 for my 7A panel. I gave up and rivited a piece of 1/2 x 1/2 x .062 angle to the bottom. Worked fine and was much easier.

Bending tip

You can try to make up some bend radiuses, use some .040" 2024-T3 or if you can get your hands on some 6061-T4 or some annealed 2024-0 .050" that will work fine, Bend up 2 or 3 pieced stacked up, make sure it's long enough for your intended bend, these bend radiuses will now be what you need to form a bigger radius to stop the cracking, if the bender has adjustment, adjust the apron to allow for the extra thickness of the material to be bent and the new bend radius.

Hope that helps,

Nick's idea for stacking thinner material within the radius is right on.
Another hint for bending aluminum is that aluminum should be bent "across" the grain. If you look closely, aluminum has a grain. Bends should be at 90° to the grain, as much as possible. Bending it "with" the grain will cause cracks.

I gave up and just riveted a piece of angle on the bottom. Works great and takes minimal time. Like Mel sez against the grain is better but the piece of stock that I got from Spruce was cut the wrong way for me to do that...and I was not about to pay for another piece since shipping cost almost as much as the stock.

Thanks Mel,

I forgot about the grain, that is the most important thing to look for before you consider the bend, also polish the ends to help stop cracking.

If it's a bit cool you can also use a heat gun to warm the metal, and bend in small increments.

If it's all too hard and the bends ends up cracking you can rivet an angle to the bottom as other have done.

Cheers,

Assuming you want a recessed switch panel on the bottom of my instrument panel, here is one way to install one.

Pick up some hardware store aluminum angle; it doesn't have the radius in the corner, so it "nestles" easier.

Rivet one piece to the bottom of the panel and then rivet a second piece under that. Secure the switch panel to the second piece with plate nuts so it is easily removable.

In my installation, after the two pieces were riveted together, plate nuts were used to secure it to the bottom of instrument panel and to secure the switch panel to the angle. That way it can be removed for future upgrades.

2024-T3 is the problem........6061-T6 will make that bend all day long.

MDR

Since it sounds like you have access to a brake at work, all you need to do is make "wrappers"; strips of thinner aluminum. Either a press brake or finger brake; same process:
Double-side-tape a strip to the male die (or fingers) and bend it (now it's stuck to either the top die or the fingers. Adjust the stroke to allow for another thickness and do it again. Now you have 2 strips taped to either the top die or fingers and you will see a bigger radius taking shape.
I have a finger brake at home and do this ALL the time; stacking as many as 3 or 4 strips of .062 thick aluminum strips. My preference is to use 5052-H32; I have a bunch of .032" and .062" sheared up into 1.0" wide strips. The alloy is not that important, the 5052-H32 is softer and easier to bend than the 2024-T6 and is softer so it doesn't mar the surface of the 2024-T6. I also like to leave the vinyl on the 2024-T6 part being bent. You are very correct in watching for stress cracks when you fabricate you own parts.

Thanks for the tips.
I'll try it with some wrapper strips

Minimum bending radius

These websites have charts giving the minimum bend radius for different thicknesses and alloys of aluminum.
Joe
http://www.precisionsheetmetal.com/home/materials.htm#Aluminum%20Bend%20Radii
http://www.engineersedge.com/sheet_metal.htm

Bending Radius

I bought a one inch wide strip of hardware-store aluminum and filed a radius along one edge with a vixen file. I placed this strip of aluminum on top of the sheet to be bent and taped it so that it would not move. Then I slid the sheet into the brake and clamped down on the strip. The brake made a nice bend with a radius and no cracks. The thickness of the aluminum strip should equal the desired radius, i.e., 1/8" thick for 1/8" radius or 1/4" thick for 1/4" radius.
Joe

I used two strips of some .032 that I had laying around.
Bend the first one, then put the second strip under it and bent the second one.
Then I put a practice piece of .050 under the strips, adjusting them so there was a small setback. The bend came out very nice. No stress cracks like my first attempt without the strips.